(a) Field of the Invention
The present invention relates to an organic thin film transistor array panel and a manufacturing method thereof.
(b) Description of the Related Art
In general, a flat panel display, such as a liquid crystal display (“LCD”), an organic light emitting diode (“OLED”) display, and an electrophoretic display, includes a plurality of pairs of field generating electrodes and an electro-optical active layer interposed therebetween. An LCD includes a liquid crystal layer as the electro-optical active layer, and an OLED display includes an organic emission layer as the electro-optical active layer.
One of the plurality of pairs of field generating electrodes is generally connected to a switching element to be applied with an electrical signal, and the electro-optical active layer converts the electrical signal into an optical signal, thereby displaying images.
Thin film transistors (“TFTs”), which are three-terminal elements, are used as switching elements in a flat panel display. Also provided in the flat panel display are gate lines for transmitting scanning signals to control the TFTs and data lines for transmitting signals to be applied to pixel electrodes.
Among TFTs, organic thin film transistors (OTFTs) using an organic semiconductor instead of an inorganic semiconductor such as silicon (Si) have been vigorously researched.
OTFTs can be easily applied to large-sized flat panel displays. The only limiting factors in OTFT fabrication are the deposition processes in which the OTFT must be formed. In particular, OTFTs may be fabricated at a low temperature by a solution process; therefore even with their limitations they are potentially advantageous. The ability to fabricate an OTFT substrate at low temperature and by a solution process allows them to be more easily manufactured, as compared to a process requiring heating or chemical development. Moreover, since an OTFT can be fabricated in the form of a fiber or a film due to the flexible characteristics of the organic material, it has been in the spotlight as a core element of a flexible display device.
However, organic semiconductors may be easily damaged during the manufacturing process due to their weak chemical resistance. Therefore, a different structure from pre-existing TFTs is required.
Also, since an organic semiconductor has a low current ratio (I-on/I-off) compared to an inorganic semiconductor, ways to improve this problem are also required.